Python边学边用--BT客户端实现之(三)Peer协议设计
与peer建立tcp连接后，首先发送handshake消息进行握手
handshake消息格式如下：
一个字节0x19 + 一个字符串'BitTorrent protocol' + 8 byte 保留字节默认值为0（draft中对保留字节有定义）
+ 种子文件中info 部分的sha1字，大小为20个字节 + 20个自己的peer id（从tracker获取到的peer信息大多没有peerid，这个可以使用本地的peer id）
如果handshake信息协商不上，tcp连接将被关闭。
BT标准BEP-3中定义了8种peer消息：消息格式为msg_len(4个字节) + msg_type(1一个字节) + payload
0 - choke --发送该消息表示本段发送阻塞，对端将不能获取到piece数据，payload 为 0
1 - unchoke --发送该消息表示解阻塞，对端可以开始发送请求获取piece数据，payload 为 0
2 - interested --发送该消息，表示对对端的pieces数据有兴趣，payload 为 0
3 - not interested ---发送该消息，表示对对端的pieces数据没有兴趣了，payload 为 0
4 - have ---发送该消息，通告对端 本段拥有的pieces，payload为4个字节的piece index
5 - bitfield ---发送该消息，通告对端 本段拥有的pieces，为bit map的方式表示每个piece index在本端是否拥有。piece index所在bit位为1，表示拥有。
该消息为handshake成功后的第一个消息。
6 - request ---piece请求消息，payload为： index, begin, and length，都是4个字节表示，length一般实现为0x8000, 最大不能超过0x20000。
7 - piece ---piece 数据，payload为： index, begin,data
8 - cancel ---发送该消息，表示本端取消了某个piece请求。payload为：index, begin, and length
使用python的同步socket接口实现，为了减少处理过程被socket阻塞，使用多个线程处理每个peer。
每个peer包括3个线程：request timeout timer ，socket send data thread， socket receive data thread
使用 RLock 保护临界数据。peer建立和piece request分配有download task线程处理。
发送数据数据时先写一个队列，然后通过set threading.Event 变量出发socket send data thread发送数据，保证发送数据的线程不阻塞
由于 python没有结束线程的接口，socket send data thread， socket receive data thread 需要依赖特殊变量的赋值，使socket处理进程结束。
使用同步调用来触发下载过程运转，尽量不使用timer轮询的方式，可以降低cpu使用率并加快下载过程。
但是，多线程间的同步调用由于锁的存在，会导致性能下降并容易引入信号量死锁的问题。需要仔细设计好多线程的运行轨迹避免死锁。
draft BEP中定义的功能暂未实现，peer的上传流控未实现，peer质量分级未实现。
10 2012 档案
Python边学边用--BT客户端实现之(三)Peer协议设计
摘要: 与peer建立tcp连接后，首先发送handshake消息进行握手handshake消息格式如下：一个字节0x19 + 一个字符串'BitTorrent protocol' + 8 byte 保留字节默认值为0（draft中对保留字节有定义）+ 种子文件中info 部分的sha1字，大小为20个字节 + 20个自己的peer id（从tracker获取到的peer信息大多没有peerid，这个可以使用本地的peer id）如果handshake信息协商不上，tcp连接将被关闭。BT标准BEP-3中定义了8种peer消息：消息格式为msg_len(4个字节) + msg_type
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posted @ 2012-10-07 23:03 duandetao 阅读(619) | 评论 (0) 编辑
Python边学边用--BT客户端实现之(二)Peers获取
摘要: 解析完torrent文件之后，需要从Tracker服务器获取拥有每个piece的peer列表。tracker服务器使用http协议提供支持，使用get的方式获取请求内容。也有使用udp协议的，暂时还没有分析。get 格式如下：announce-url?info_hash=xxxxxxxxxxxxxxxxxxxxx,peer_id=xxxxxxxxxxxxxxxxxxxx,ip=x.x.x.x,port=xxxx,uploaded=xx,downloaded=xx,left=xx,event=xurl中各参数需要经过url扰码处理。其中，info_hash为torrent文件中info属性的va
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posted @ 2012-10-02 20:09 duandetao 阅读(221) | 评论 (0) 编辑
09 2012 档案
Python边学边用--BT客户端实现之（一）BitTorrent文件解析
摘要: BitTorrent文件解析：BitTorrent文件使用bencode编码，其中包括了4种数据类型：'d' 开头表示是dict类型，'e'表示结束'l' （小写字母L）开头表示是list类型，'e'表示结束'i'开头表示是integer类型，'e'表示结束，可以表示负数以数字开头表示string类型，数字为string长度，长度与string内容以':'分割默认所有text类型的属性为utf-8编码，但是大多数BitTorrent包含codepage 和 encoding属性，指定
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posted @ 2012-09-29 23:17 duandetao 阅读(1038) | 评论 (2) 编辑
1 ''' 2 Created on 2012-9-29 3 4 @author: ddt 5 ''' 6 import torrent_file 7 import bcodec 8 import random 9 import threading 10 from trackers_info import * 11 import socket 12 from peer_connect import PeerConnect 13 import os 14 import time 15 import log_info 16 17 class DownLoadTask(object): 18 ''' 19 TODO: UPNP support 20 TODO: local listening support 21 TODO: threading safety 22 TODO: DHT support 23 TODO: flow control support 24 ''' 25 def __init__(self): 26 ''' 27 Constructor 28 ''' 29 self.__host_ip, self.__host_port = _get_listening_addr(); 30 self.__bt_file = torrent_file.TorrentFile() 31 self.__peer_id = '' 32 self.__download_state = {} 33 self.__files = [] 34 self.__info_hash = None 35 self.__piece_length = 0 36 37 self.__trackers_info = None 38 39 self.__pieces_refresh_intvl = 30 # second 40 self.__pieces_refresh_timer = None 41 self.__piece_max_unread_time = 20 42 43 self.__unchoked_peers = {} 44 self.__choked_peers = {} 45 self.__max_pieces_per_peer = 50 46 47 self.__rlock_common = threading.RLock() 48 49 self.__base_path = '.\\' 50 51 pass 52 53 def start_task(self, bt_file_name): 54 with self.__rlock_common: 55 try: 56 self.__bt_file.read_file(bt_file_name) 57 except (IOError,torrent_file.BTFormatError), reason: 58 self.__write_log("Read bittorrent file error! Error:%s" %str(reason)) 59 return False 60 61 self.__peer_id = _generate_peerid() 62 self.__files = self.__bt_file.get_files() 63 self.__info_hash = self.__bt_file.get_info_hash() 64 65 self.__piece_length = self.__bt_file.get_piece_length() 66 67 self.__download_state['downloaded'] = 0 68 self.__download_state['uploaded'] = 0 69 self.__download_state['left'] = self.__get_total_length() 70 self.__download_state['event'] = 'started' 71 self.__download_state['pieces-num'] = self.__bt_file.get_pieces_num() 72 self.__download_state['downloading-pieces'] = {} 73 self.__download_state['waiting-pieces'] = {} 74 self.__download_state['completed-pieces'] = {} 75 76 self.__writingfile_pieces = [] 77 78 self.__trackers_info = TrackersInfo(self) 79 80 self.__init_files() 81 82 self.__init_pieces_state() 83 84 self.__trackers_info.start_trackers_refresh() 85 86 self.__start_pieces_refresh() 87 88 return True 89 90 def tacker_get_peers(self, peers): 91 with self.__rlock_common: 92 self.__try_new_peers(peers) 93 self.__dispatch_pieces() 94 95 def get_announce_list(self): 96 return self.__bt_file.get_announces() 97 98 def get_download_stat(self): 99 with self.__rlock_common: 100 downloaded = self.__download_state['downloaded'] 101 uploaded = self.__download_state['uploaded'] 102 left = self.__download_state['left'] 103 event = self.__download_state['event'] 104 return (downloaded,uploaded,left,event) 105 106 def get_host_info(self): 107 host_info = (self.__peer_id, self.__host_ip, self.__host_port) 108 return host_info 109 110 def get_info_hash(self): 111 return self.__info_hash 112 113 def get_local_id(self): 114 return self.__peer_id 115 116 def get_local_have_pieces(self): 117 with self.__rlock_common: 118 return self.__download_state['completed-pieces'].keys() 119 120 def get_pieces_num(self): 121 return self.__bt_file.get_pieces_num() 122 123 def peer_pieces_canceled(self, pieces): 124 print 'peer_pieces_canceled:%s' %str(pieces) 125 126 with self.__rlock_common: 127 for piece_index in pieces: 128 if piece_index in self.__download_state['downloading-pieces'].keys(): 129 self.__undownload_piece(piece_index) 130 131 self.__dispatch_pieces() 132 133 def peer_have_pieces(self,peer_con, pieces): 134 self.__write_log('peer_have_pieces:%s' %str(pieces)) 135 with self.__rlock_common: 136 self.__dispatch_peer_pieces(peer_con, pieces) 137 138 def peer_pieces_completed(self, peer_con): 139 self.__write_log('peer_pieces_completed:%s' %str(peer_con.get_peer_addr())) 140 with self.__rlock_common: 141 self.__dispatch_peer_pieces(peer_con) 142 143 def peer_choked(self, peer_con): 144 with self.__rlock_common: 145 peer_addr = peer_con.get_peer_addr() 146 if peer_addr in self.__unchoked_peers.keys(): 147 self.__unchoked_peers.pop(peer_addr) 148 self.__choked_peers[peer_con.get_peer_addr()] = peer_con 149 150 #peeding_pieces = peer_con.get_local_pending_pieces() 151 #peer_con.cancel_pieces(peeding_pieces) 152 #self.peer_pieces_canceled(peeding_pieces) 153 154 def peer_unchoked(self, peer_con): 155 with self.__rlock_common: 156 peer_addr = peer_con.get_peer_addr() 157 if peer_addr in self.__choked_peers.keys(): 158 self.__choked_peers.pop(peer_addr) 159 self.__unchoked_peers[peer_con.get_peer_addr()] = peer_con 160 self.__dispatch_peer_pieces(peer_con) 161 162 def peer_dead(self, peer_con): 163 with self.__rlock_common: 164 peer_addr = peer_con.get_peer_addr() 165 if peer_addr in self.__choked_peers.keys(): 166 self.__choked_peers.pop(peer_addr) 167 168 if peer_addr in self.__unchoked_peers.keys(): 169 self.__unchoked_peers.pop(peer_addr) 170 171 def write_piecedata(self, piece_index, offset, data): 172 with self.__rlock_common: 173 if piece_index in self.__download_state['downloading-pieces'].keys(): 174 piece_state = self.__download_state['downloading-pieces'][piece_index] 175 176 if offset == piece_state['waiting-offset']: 177 self.__piece_install_data(piece_state, data) 178 179 while len(piece_state['disorder-data']) != 0: 180 curr_offset = piece_state['waiting-offset'] 181 if curr_offset in piece_state['disorder-data'].keys(): 182 self.__piece_install_data(piece_state, piece_state['disorder-data'][curr_offset]) 183 else: 184 break 185 else: 186 piece_state['disorder-data'][offset] = data 187 188 return 189 190 self.__write_log('unexpected piece data: %s' %str((piece_index,offset,data))) 191 192 def read_piecedata(self, piece_index, offset, length): 193 with self.__rlock_common: 194 if piece_index in self.__download_state['completed-pieces'].keys(): 195 piece_state = self.__download_state['completed-pieces'][piece_index] 196 197 if piece_state['waiting-offset'] == 0: 198 self.__read_from_file(piece_state) 199 200 if offset + length <= piece_state['waiting-offset']: 201 piece_state['unread-time'] = 0 202 return piece_state['piece-data'][offset:offset+length] 203 204 self.__write_log('read piece date but not hava:%s' %str((piece_index, offset, length))) 205 206 def __piece_install_data(self, piece_state, data): 207 piece_state['waiting-offset'] += len(data) 208 piece_state['piece-data'] += data 209 210 if piece_state['waiting-offset'] >= self.__piece_length: 211 piece_state['disorder-data'].clear() 212 self.__complete_piece(piece_state['piece-index']) 213 214 if piece_state['waiting-offset'] > self.__piece_length: 215 piece_state['piece-data'] = piece_state['piece-data'][0:self.__piece_length] 216 piece_state['waiting-offset'] = self.__piece_length 217 self.__write_log('piece data is too much:%s' %str(piece_state['piece-index'])) 218 219 self.__download_state['downloaded'] += piece_state['waiting-offset'] 220 self.__download_state['left'] -= piece_state['waiting-offset'] 221 222 def __read_from_file(self, piece_state): 223 piece_index = piece_state['piece-index'] 224 files = piece_state['file-info'] 225 one_file = files[0] 226 first_piece = one_file['first-piece'] 227 last_piece = one_file['last-piece'] 228 if first_piece[0] <= piece_index or piece_index <= last_piece[0]: 229 file_offset = (piece_index - first_piece[0])*self.__piece_length - first_piece[1] 230 file_handle = open(self.__base_path+'\\'.join(one_file['name']),'rb') 231 file_handle.seek(file_offset) 232 data = file_handle.read(self.__piece_length) 233 file_handle.close() 234 piece_state['piece-data'] = data 235 piece_state['waiting-offset'] = self.__piece_length 236 piece_state['unread-time'] = 0 237 238 def __write_piece_to_file(self, piece_state): 239 self.__write_log('__write_piece_to_file') 240 241 piece_index = piece_state['piece-index'] 242 data = piece_state['piece-data'] 243 244 for one_file in piece_state['file-info']: 245 first_piece = one_file['first-piece'] 246 last_piece = one_file['last-piece'] 247 if first_piece[0] <= piece_index or piece_index <= last_piece[0]: 248 file_offset = (piece_index - first_piece[0])*self.__piece_length - first_piece[1] 249 else: 250 continue 251 piece_offset = 0 252 if first_piece[0] == piece_index: 253 piece_offset = first_piece[1] 254 255 write_file_len = self.__piece_length - piece_offset 256 if last_piece[0] == piece_index: 257 write_file_len = last_piece[1] - piece_offset 258 259 file_path = self.__base_path+'\\'.join(one_file['name']) 260 file_handle = open(file_path,'rb+') 261 file_handle.seek(file_offset) 262 data = file_handle.write(data[piece_offset:piece_offset+write_file_len]) 263 file_handle.close() 264 self.__write_log('write data to file:%s' %str((file_path, file_offset, write_file_len))) 265 266 self.__write_log('__write_piece_to_file end') 267 268 def __get_total_length(self): 269 total_length = 0 270 for one_file in self.__files: 271 total_length += one_file['length'] 272 return total_length 273 274 def __init_files(self): 275 self.__write_log( '__init_files') 276 for one_file in self.__files: 277 278 path = self.__base_path 279 for dir in one_file['name'][:-1]: 280 path += dir+'.\\' 281 if not os.path.exists(path): 282 os.mkdir(path) 283 284 file_path = self.__base_path + '\\'.join(one_file['name']) 285 286 if os.path.exists(file_path): 287 break 288 289 file_length = one_file['length'] 290 file_handle = open(file_path,'ab+') 291 dumy_data = chr(0)*0x4000 292 for i in range(0,file_length, 0x4000): 293 write_len = 0x4000 294 if i+write_len > file_length: 295 write_len = file_length - i 296 file_handle.write(dumy_data[0:write_len]) 297 file_handle.close() 298 pass 299 300 def __init_pieces_state(self): 301 self.__write_log( '__init_pieces_state') 302 pieces_state = {} 303 for one_file in self.__files: 304 for piece_index in range(one_file['first-piece'][0], one_file['last-piece'][0] + 1): 305 if piece_index not in pieces_state.keys(): 306 piece_state = {} 307 piece_state['connect-info'] = None 308 piece_state['file-info'] = [one_file] 309 310 piece_state['waiting-offset'] = 0 311 piece_state['piece-data'] = '' 312 piece_state['disorder-data'] = {} 313 314 piece_state['piece-index'] = piece_index 315 316 piece_state['unread-time'] = 0 317 pieces_state[piece_index] = piece_state 318 else: 319 pieces_state[piece_index]['file-info'] += one_file 320 self.__download_state['waiting-pieces'] = pieces_state 321 pass 322 323 def __start_pieces_refresh(self): 324 if self.__pieces_refresh_timer != None: 325 self.__pieces_refresh_timer.cancel() 326 327 refresh_thread = threading.Thread(target=DownLoadTask.__refresh_pieces_state, args=(self,)) 328 refresh_thread.start() 329 330 def __refresh_pieces_state(self): 331 self.__write_log( '__refresh_pieces_state') 332 333 with self.__rlock_common: 334 for piece_state in self.__download_state['completed-pieces'].values(): 335 if piece_state['waiting-offset'] != 0: 336 piece_state['unread-time'] += 1 337 338 if len(piece_state['file-info']) >= 2 and piece_state['unread-time'] > self.__piece_max_unread_time: 339 piece_state['waiting-offset'] = 0 340 piece_state['piece-data'] = '' 341 piece_state['unread-time'] = 0 342 343 self.__check_files_completed() 344 345 if self.__pieces_refresh_timer != None: 346 self.__pieces_refresh_timer.cancel() 347 348 self.__pieces_refresh_timer = threading.Timer(self.__pieces_refresh_intvl,\ 349 DownLoadTask.__refresh_pieces_state, [self,]) 350 self.__pieces_refresh_timer.start() 351 352 self.__dispatch_pieces() 353 self.__write_log( '__refresh_pieces_state end') 354 355 def __notify_peers_have(self, have_pieces): 356 self.__write_log('__notify_peers_have') 357 with self.__rlock_common: 358 for peer_con in self.__unchoked_peers.values(): 359 peer_con.notify_local_have_pieces(have_pieces) 360 361 for peer_con in self.__choked_peers.values(): 362 peer_con.notify_local_have_pieces(have_pieces) 363 364 def __try_new_peers(self, peers): 365 with self.__rlock_common: 366 for peer in peers: 367 if peer not in self.__unchoked_peers.keys() and peer not in self.__choked_peers.keys(): 368 peer_con = PeerConnect(peer[0],peer[1],self) 369 self.__choked_peers[peer] = peer_con 370 peer_con.start() 371 372 def __check_files_completed(self): 373 self.__write_log( '__check_files_completed') 374 completed_pieces = self.__download_state['completed-pieces'].keys() 375 completed_pieces = set(completed_pieces) 376 writingfile_pieces = set(self.__writingfile_pieces) 377 378 for one_file in self.__files: 379 file_path = self.__base_path + '.\\'.join(one_file['name']) 380 381 first_piece = one_file['first-piece'] 382 last_piece = one_file['last-piece'] 383 384 file_pieces = range(first_piece[0], last_piece[0]+1) 385 file_pieces = set(file_pieces) 386 387 need_writefile = file_pieces & writingfile_pieces 388 if len(need_writefile) != 0: 389 file_handle = open(file_path, 'ab+') 390 for piece_index in need_writefile: 391 392 piece_state = self.__download_state['completed-pieces'][piece_index] 393 if len(piece_state['file-info']) > 1: 394 self.__write_piece_to_file(piece_state) 395 writingfile_pieces.remove(piece_index) 396 continue 397 398 data = piece_state['piece-data'] 399 file_offset = (piece_index - first_piece[0])*self.__piece_length - first_piece[1] 400 file_handle.seek(file_offset) 401 file_handle.write(data) 402 self.__write_log( 'writing data to file:%s,%s' %(piece_index,file_path)) 403 file_handle.close() 404 405 if file_pieces <= completed_pieces: 406 one_file['completed'] = True 407 self.__write_log( 'file:%s completed!' %file_path) 408 409 self.__writingfile_pieces = [] 410 411 def __dispatch_pieces(self): 412 self.__write_log( '__dispatch_pieces') 413 for peer_con in self.__unchoked_peers.values(): 414 if len(self.__download_state['waiting-pieces'].keys()) == 0: 415 break 416 417 self.__dispatch_peer_pieces(peer_con) 418 419 for peer_con in self.__choked_peers.values(): 420 if len(self.__download_state['waiting-pieces'].keys()) == 0: 421 break 422 423 self.__dispatch_peer_pieces(peer_con) 424 425 def __dispatch_peer_pieces(self, peer_con, peer_have_pieces = None): 426 self.__write_log( '__dispatch_peer_pieces') 427 428 peer_pending_pieces = peer_con.get_local_pending_pieces() 429 dispatching_num = self.__max_pieces_per_peer - len(peer_pending_pieces) 430 if dispatching_num <= 0: 431 return 432 433 if peer_have_pieces == None: 434 peer_have_pieces = peer_con.get_peer_have_pieces() 435 436 peer_have_pieces = set(peer_have_pieces) 437 438 if len(peer_have_pieces) == 0: 439 return 440 441 waiting_pieces = set(self.__download_state['waiting-pieces'].keys()) 442 443 if len(waiting_pieces) == 0: 444 return 445 446 dispatching_pieces = peer_have_pieces & waiting_pieces 447 448 dispatching_pieces = list(dispatching_pieces) 449 dispatching_pieces = dispatching_pieces[0:dispatching_num] 450 if len(dispatching_pieces) == 0: 451 return 452 453 if peer_con.dispatch_pieces(dispatching_pieces, self.__piece_length): 454 for piece_index in dispatching_pieces: 455 self.__download_piece(piece_index, peer_con) 456 self.__write_log( 'dispatch_pieces:%s,%s' %(str(dispatching_pieces),str(peer_con.get_peer_addr()))) 457 pass 458 459 def __complete_piece(self, piece_index): 460 piece_state = self.__download_state['downloading-pieces'].pop(piece_index, None) 461 if piece_state == None: 462 return 463 self.__download_state['completed-pieces'][piece_index] = piece_state 464 piece_state['connect-info'] = None 465 self.__notify_peers_have([piece_index,]) 466 self.__writingfile_pieces.append(piece_index) 467 468 def __undownload_piece(self, piece_index): 469 piece_state = self.__download_state['downloading-pieces'].pop(piece_index, None) 470 if piece_state == None: 471 return 472 self.__download_state['waiting-pieces'][piece_index] = piece_state 473 474 self.__download_state['left'] += piece_state['waiting-offset'] 475 self.__download_state['downloaded'] -= piece_state['waiting-offset'] 476 piece_state['waiting-offset'] = 0 477 piece_state['piece-data'] = '' 478 piece_state['connect-info'] = None 479 480 def __download_piece(self, piece_index, peer_con): 481 piece_state = self.__download_state['waiting-pieces'].pop(piece_index, None) 482 if piece_state == None: 483 return 484 485 self.__download_state['downloading-pieces'][piece_index] = piece_state 486 piece_state['waiting-offset'] = 0 487 piece_state['piece-data'] = '' 488 piece_state['connect-info'] = peer_con 489 490 def __write_log(self,log): 491 log_info.write_log(log) 492 pass 493 494 def _generate_peerid(): 495 peerid = '' 496 for i in range(0,20): 497 peerid += chr(random.randrange(ord('a'),ord('z'))) 498 return peerid 499 500 def _get_listening_addr(): 501 host_ip = socket.gethostbyname(socket.gethostname()) 502 host_port = 6881 503 return host_ip,host_port 504 505 if __name__ == '__main__': 506 new_task = DownLoadTask() 507 new_task.start_task(r".\narodo.torrent") 508 time.sleep(100000) 509